Interpretive Summary: Phytophthora rot and soybean cyst nematode are serious yield-limiting diseases of soybean. In order to mitigate yield losses caused by these two diseases, it was essential to develop germplasm with traits having high yield and multiple pest resistance. Because Bedford has a moderate level of resistance to race 14 of soybean cyst nematode and is highly resistant to race 3 of phytophthora rot, it was used as one of the parents in the breeding experiment. As a result, soybean germplasm line D98-1218 was developed and released in October 2003. This line has value because of its resistance to phytophthora rot and races 3 and 14 of soybean cyst nematode. It also has value to the private and public soybean breeders because it will expand the set of previous releases of phytophthora rot resistant lines

Technical Abstract:
Soybean germplasm line D98-1218 was released in October 2003. The objective was to provide private and public soybean breeders with a parent to develop high yielding, multiple pest resistant cultivars. Phytophthora rot (PR) and soybean cyst nematode (SCN) continue to be serious yield-limiting diseases of soybean. D98-1218 is a product of a backcrossing program to transfer the Rps2 gene into a 'Bedford' background. This line has value as a parent because of its resistance to PR and races 3 and 14 of the soybean cyst nematode. It also has value to the research community because it will expand the set of previous releases of PR-resistant lines which are near-isogenic to the cultivar Bedford. The reaction of 12 F3 plants was used to identify lines uniformly resistant to PR. F2:3 lines uniformly resistant to PR were selected as pollen parents between each of the five crossing cycles. Seedlings were inoculated in a greenhouse during the years 2002 and 2003 by the hypocotyl puncture method using race 2 of the pathogen. After the fourth backcross to Bedford, an F3 line uniformly resistant to race 2 was increased for two generations, and 100 F5 plants were again inoculated with race 2 to verify the reaction of the F3. D98-1218 was evaluated in F8 generation for reaction to races 3 and 14 of the SCN at Jackson, TN. D98-1218 had a similar level of resistance to races 3 and 14 as the recurrent parent, Bedford. In a yield test (three replications) on clay soil at Stoneville, MS in 1999, D98-1218 yielded 3968.2 kg ha-1, compared with 3804.6 kg ha-1 for Bedford. Under very high temperatures during seed fill in 2000, seed yields were very low. Yield of D98-1218 was 1786.4 kg ha-1 compared with a yield of 1281.8 kg ha-1 for Bedford. In 2001, again under very poor yielding conditions, D98-1218 yielded 2386.4 kg ha-1 compared with a yield of 1015.9 kg ha-1 for Bedford. Under a more favorable yielding environment in 2002, D98-1218 yielded 3920.5 kg ha-1 compared with a yield of 3313.6 kg ha-1 for Bedford